MC4 receptor raises a handful of sensible questions. This page answers them in order, starting with the fundamentals and moving to applications.
This page was last updated on 2026-05-30 and is reviewed periodically as new material appears.
Published studies examine a fairly narrow set of endpoints. Rodent experiments commonly measure maze learning, infarct volume after induced ischemia, and tissue levels of neurotrophic factors. Clinical reports from Russian centres describe attention, memory and recovery scores in patients after stroke or transient ischemic attack. Most of those human studies are small and few have been repeated by independent groups. Outcome measures differ between studies, which limits direct comparison.
Circulation time for the peptide is short because peptidases cleave it readily. The Pro-Gly-Pro tail is thought to slow breakdown compared with the bare ACTH fragment, but the gain appears modest. Absorption after intranasal dosing is limited, and only a fraction of a dose is expected to reach the central nervous system. Laboratory concentrations therefore sit well above levels achieved systemically, a gap that complicates translation from bench findings to clinical claims.
The mechanisms attributed to semax are inferred from animal and cell studies rather than traced to one confirmed target. The most frequently cited pathway involves increased expression of brain-derived neurotrophic factor and nerve growth factor in hippocampal and cortical tissue. Some work points to engagement of melanocortin receptors, particularly MC4, which the parent ACTH fragment can activate. Effects on dopaminergic and serotonergic signalling have also been reported. No single account explains all observed results, and the relative weight of each pathway remains unsettled.
Semax is a synthetic seven-amino-acid peptide whose sequence extends the ACTH(4-10) fragment with a C-terminal proline-glycine-proline tripeptide. The commonly cited sequence is Met-Glu-His-Phe-Pro-Gly-Pro, giving a molecular formula near C37H51N9O10S and a molecular weight close to 813.9 g/mol. It belongs to the broader class of synthetic ACTH fragments studied for central nervous system effects rather than for adrenal steroid stimulation. In practice the material appears as a lyophilized white powder for laboratory work or as a dilute saline solution in clinical settings.
Development is attributed to researchers at the Institute of Molecular Genetics in Moscow during the early 1980s, building on earlier Soviet work with ACTH fragments. Russian regulatory approval followed for intranasal use, and the compound has remained commercially available there for decades. Most published human data originate from Russian and, later, some Eastern European clinical reports, which are not always accessible in English translation. Outside that region the material is generally handled as a research chemical rather than a licensed medicine.
| Property | Value | Notes |
|---|---|---|
| Appearance | White to off-white powder | Lyophilized solid from research suppliers |
| Solubility | Freely soluble in water | Also dissolves in aqueous buffers; solutions are used fresh |
| Typical storage temperature | -20 °C for lyophilized powder | Short-term transport at 2-8 °C is common |
| Common analytical method | Reverse-phase HPLC | Paired with mass spectrometry for identity confirmation |
| Common synonyms | ACTH(4-10) analogue; MEHFPGP | N-terminal methionine retained in the chain |
Common degradation pathways include oxidation of the methionine side chain, hydrolysis of the peptide backbone, and aggregation under unfavourable pH or concentration. Stability studies typically monitor the main peak by chromatography and report total related substances as a percentage. Because no official monograph exists, acceptance criteria vary between laboratories, and reported purity values are not directly comparable across suppliers. Analysts therefore document the method, column, and detection wavelength alongside each result, and open questions remain about how much biological activity the oxidised forms retain.
Solid semax is typically supplied as a lyophilised powder that is hygroscopic and sensitive to moisture, light, and repeated temperature cycling. Long-term storage of the dry peptide is generally recommended at approximately -20 degrees Celsius, while shorter working periods may use refrigeration at 2 to 8 degrees Celsius. Vials should remain tightly closed and desiccated when brought to room temperature, because condensation can damage the material before it is weighed. Dividing a batch into aliquots is preferable to thawing one container repeatedly.
Dissolution is normally performed in water, phosphate-buffered saline, or normal saline, since the peptide is freely soluble in aqueous media and is rarely handled with strong organic solvents. Solution pH should be kept near neutral, because extreme acidity or alkalinity accelerates backbone hydrolysis and encourages oxidation of the methionine side chain. Once dissolved, the material is less stable than the dry powder and is commonly divided into single-use portions and frozen. Buffers containing primary amines, such as Tris, are often avoided because of possible side reactions.
Semax 是人工设计的七肽，序列为 Met-Glu-His-Phe-Pro-Gly-Pro，骨架取自促肾上腺皮质激素片段 ACTH(4-10)。它于二十世纪八十年代在苏联的分子遗传学研究机构内合成。设计目标是保留该片段与注意力和记忆相关的活性，同时剔除促皮质激素释放等内分泌作用。此后俄罗斯将其登记为药品并进入临床使用。
当时的短肽研究普遍关注能否穿越血脑屏障、在低剂量下产生中枢效应，Semax 属于这一路线。鼻内给药是其主要使用方式，俄语文献报道的适应症涵盖缺血性卒中、短暂性脑缺血发作、认知功能减退以及视神经病变。这些研究大多发表在当地期刊上，样本规模与终点设置同西方试验惯例存在差异，国际同行对其临床证据的强度看法不一。
各国监管态度分化明显。俄罗斯按处方药管理，部分东欧国家留有使用记录；欧盟与美国未批准其作为药物上市，市面流通品通常标注为研究用化学品。身份差异意味着标示含量、纯度与无菌性缺少统一核查。体育领域还牵涉反兴奋剂名录，跨境携带则受目的地药品法规约束。
Identity and purity are confirmed with reversed-phase high-performance liquid chromatography, typically monitored at 214 nanometres where the peptide bond absorbs. Mass spectrometry, either electrospray or MALDI-TOF, verifies molecular mass against the theoretical value and detects truncation or adduct formation. Amino acid analysis and peptide mapping provide additional confirmation when required. The most frequently reported impurities are deletion sequences from incomplete coupling, methionine sulfoxide from oxidation, and dimeric species formed through non-covalent aggregation. Impurity profiles depend strongly on the synthesis and purification route chosen by the producer.
Published research has focused mainly on neurological and cognitive endpoints in animal models, with proposed mechanisms involving brain-derived neurotrophic factor and related signalling pathways. A substantial share of the human data originates from a limited number of research groups, and independent replication in other countries remains sparse. Regulatory status reflects that distribution: the peptide is registered as a medicine in Russia and appears in some neighbouring markets, while elsewhere it is handled as a research chemical without approved therapeutic labelling. Questions about dose-response relationships, long-term effects, and comparability across studies are still open.
Lyophilised powder is normally kept at -20 °C in a desiccated container, with some suppliers recommending -80 °C for long-term archival storage. Repeated freeze-thaw cycles are the most common cause of avoidable loss, so aliquoting before freezing reduces variability between working sessions. Dissolved peptide is far less stable than the dry solid and is usually prepared fresh or held briefly at 4 °C. Aqueous solutions support both hydrolysis of the backbone and oxidation of the N-terminal methionine, and these two routes dominate degradation under ordinary laboratory conditions.
Semax is a synthetic heptapeptide with the sequence Met-Glu-His-Phe-Pro-Gly-Pro. It corresponds to the ACTH(4-7) fragment extended at the C-terminus by a Pro-Gly-Pro tripeptide, an addition intended to slow enzymatic breakdown. The molecular formula is C37H51N9O10S and the molecular mass is approximately 814 daltons. In the literature it is often described as an ACTH(4-10) analog, although that label reflects a naming convention as much as a precise structural relationship. The compound was developed in Russia and remains most closely associated with that research tradition.
Laboratory descriptions of the material are consistent across suppliers. It appears as a white to off-white lyophilized powder that dissolves readily in water and in polar organic solvents such as dimethyl sulfoxide. Aqueous solutions are clear and colorless at low concentrations. Because the peptide contains methionine, oxidation at the sulfur atom is a recognized degradation pathway, and handling notes usually call for protected, desiccated storage. Reported purity for research-grade lots is generally above 95 percent as measured by reversed-phase high-performance liquid chromatography.
The compound is registered in Russia as a pharmaceutical product, most commonly formulated as a nasal solution, and has been used in that setting since the 1990s. Outside that jurisdiction it is generally handled as a research chemical rather than an approved medicine. Regulatory status therefore differs sharply between countries, and material sold internationally may not correspond to the Russian pharmaceutical formulation. Documentation with commercial samples is typically limited to a certificate of analysis covering purity and identity, not clinical status or local legal classification.
== Side effects == Benzocaine is generally well tolerated and non-toxic when applied topically as recommended. However, there have been reports of serious, life-threatening adverse effects (e.g., seizures, coma, irregular heart beat, respiratory depression) with over-application of topical products or when applying topical products that contain high concentrations of benzocaine to the skin. The topical use of higher concentration (10–20%) benzocaine products applied to the mouth or mucous membranes has been found to be a cause of methemoglobinemia, a disorder in which the amount of oxygen carried by the blood is greatly reduced. Benzocaine may cause allergic reactions. These include:
=== 1953 === January 20: Dwight D. Eisenhower becomes President, with John Foster Dulles as Secretary of State. February 3: The Batepá massacre occurred in São Tomé and Príncipe. February 28: Balkan Pact is signed by Yugoslavia, Greece and Turkey. The pact's main objective is to deter Soviet expansionism. March 5: Stalin dies, setting off a power struggle to succeed him. NATO debates possibility of a fresh start. May 31–June 2: The 1953 Plzeň uprising was violently suppressed by the Czechoslovak government. June 2: Elizabeth II is crowned Queen of the United Kingdom and the other Commonwealth realms, at Westminster Abbey. June 17: Uprising of 1953 in East Germany crushed by Soviet troops. July 26: The Cuban Revolution begins as the 26th of July Movement led by Fidel Castro attempts to overthrow the government of Fulgencio Batista. July 27: An armistice agreement ends fighting in the Korean War, after Eisenhower threatens the use of nuclear weapons. August 19: The Central Intelligence Agency (CIA) and the British MI6 assists a royalist coup that restores Mohammad Reza Pahlavi to power as the Shah of Iran and ousts Prime Minister Mohammed Mosaddeq (Operation Ajax). The coup was organized because of Iranian nationalization of the oil industry and fears of Iran joining the Soviet camp. September 7: Nikita Khrushchev becomes leader of the Communist Party of the Soviet Union. His main rival, Lavrentiy Beria, is executed in December. September 23: The Pact of Madrid is signed by Spain and the United States.
Two or more of these techniques are often combined. This can improve preservation and reduce unwanted side effects such as the denaturation of nutrients by severe heat treatments. Common combinations are salting/drying, salting/marinating, salting/smoking, drying/smoking, pasteurization/refrigeration and controlled atmosphere/refrigeration. Other process combinations are currently being developed along the multiple hurdle theory.
Sources: en.wikipedia.org
A study of children admitted to hospital in Rawalpindi, Pakistan, found that 52.1% of the bottles their caregivers considered clean were actually contaminated. This occurred even though caregivers reportedly followed many of the recommended cleaning practices for cleaning and sterilizing bottles. The most common mistake was to boil the bottles for less than the minimum time recommended by WHO. Research into the preparation of infant formula in South Korea indicates significant levels of contamination can be transmitted through the handling of spoons and other utensils. Spoons, after being touched, were often left in the formula container, allowing bacteria to spread to the formula in the container. C. sakazakii, S. enterica, and S. aureus, all of which are potentially fatal, were able to surviving for weeks in contaminated infant formula. Understanding how recommendations are interpreted is important: in one study, leaving a bottle in water that had been previously boiled in a kettle was believed to be "boiling" the bottle. Researchers emphasize that health providers need to better educate caregivers; and that practical methods of bottle hygiene need to be suited to use in field settings. For example, in Peru, easy-to-adopt practices like using a bottle brush and detergent gave greater advantages than difficult-to-achieve procedures like boiling a bottle. WHO (which strongly recommends breastfeeding) notes that in cases where bottle feeding is to occur, much better education is needed on how to use bottles.
== Applications == Cyclic voltammetry (CV) has become an important and widely used electroanalytical technique in many areas of chemistry. It is often used to study a variety of redox processes, to determine the stability of reaction products, the presence of intermediates in redox reactions, electron transfer kinetics, and the reversibility of a reaction. It can be used for electrochemical deposition of thin films or for determining suitable reduction potential range of the ions present in electrolyte for electrochemical deposition. CV can also be used to determine the electron stoichiometry of a system, the diffusion coefficient of an analyte, and the formal reduction potential of an analyte, which can be used as an identification tool. In addition, because concentration is proportional to current in a reversible, Nernstian system, the concentration of an unknown solution can be determined by generating a calibration curve of current vs. concentration. In cellular biology, it is used to measure the concentrations of target molecules (such as specific proteins or DNA) or flow of conductive ions in living organisms. In organometallic chemistry, it is used to evaluate redox mechanisms.
Knoxville's first major annexation following the Civil War came in 1869, when it annexed the city of East Knoxville, an area east of First Creek that had incorporated in 1856. In 1883, Knoxville annexed Mechanicsville, which had developed just northwest of the city as a village for Knoxville Iron Company and other factory workers. In the 1870s and 1880s, the development of Knoxville's streetcar system (electrified by William Gibbs McAdoo in 1890) led to the rapid development of suburbs on the city's periphery. Neighborhoods such as Fort Sanders, Fourth and Gill, Old North Knoxville, Happy Holler, and Parkridge, are all rooted in "streetcar suburbs" developed during this period. In 1888, the area now consisting of Fort Sanders and the UT campus were incorporated as the City of West Knoxville, and in 1889, the area now consisting of Old North Knoxville and Fourth and Gill incorporated as the City of North Knoxville. Knoxville annexed both in 1897. In 1907, Parkridge, Chilhowee Park, and adjacent neighborhoods incorporated as Park City. Lonsdale, a factory village northwest of the city, and Mountain View, located south of Park City, incorporated that same year. Oakwood, which developed alongside the Southern Railway's Coster rail yard, was incorporated in 1913. In 1917, Knoxville annexed these four cities, along with the burgeoning suburb of Sequoyah Hills and parts of South Knoxville, effectively more than doubling the city's population, and increasing its land area from 4 to 26 square miles (10 to 67 km2).
=== Stability === Due to their role as structural stabilizers in epithelial cells, keratin filaments have garnered significant interest across biology, embryology, pathology, and dermatology. This fundamental cytoskeletal function extends beyond individual cell levels. Typically, keratin filaments are integrated into desmosomes (see Fig. 1b, d) and hemidesmosomes, contributing not only to cell-to-cell stability but also to the attachment to the basement membrane and the connective tissue within a particular epithelium. In non-stratified (simple) epithelia of internal organs experiencing minimal mechanical stress, only a few keratin types form sparsely distributed filaments within the cytoplasm. However, a more substantial number of keratin types participate in the intermediate filament cytoskeletal framework of squamous epithelia, which becomes more prominent in cornified stratified epithelia like the epidermis covering the body's outer surface. Here, keratins are abundant and densely packed, forming tonofilaments.
Sources: en.wikipedia.org
It consists mainly of animal experiments and small clinical reports, with much of the clinical material published in Russian-language journals. Large independent trials are scarce. Separating reliable effects from chance findings is consequently difficult.
A fraction of an intranasal dose is thought to reach the central nervous system, and this route is favoured partly for that reason. The proportion is not well characterized. Direct measurement in humans remains difficult with current methods.
Raised BDNF and NGF expression has been reported across several animal studies, which makes the signal fairly consistent. Whether the same change occurs in humans at usable doses is not established. It is best treated as a working hypothesis rather than a confirmed clinical mechanism.
It is a short synthetic peptide built from seven amino acids: methionine, glutamic acid, histidine, phenylalanine and three prolines. The sequence derives from the 4-10 fragment of adrenocorticotropic hormone with an added proline-glycine-proline tail. No plant or animal extract is involved; the material is produced by solid-phase peptide synthesis.